Study On Loading Technology And Sterilization Activities Of Silver-modified Titanium Dioxide And Bismuth Vanadate Photocatalysts On Glazed Ceramic Tiles

A large number of pathogenic microorganisms are prone to breed in the dark and humid place in the toilet.These pathogenic microorganisms are widely distributed on the surface of various facilities in the toilet,which is easy to spread various diseases.Due to the photocatalytic material has the function of pollutant degradation,sterilization and superhydrophilicity,the photocatalyst is loaded on the surface of toilet cleaners to make it self-cleaning and bactericidal,which will greatly improve the sanitary conditions of toilets.However,the technical parameters of the control of the photocatalytic material loaded on the surface porcelain of the cleaning material have not been fully understood,and the technology that takes into account the bactericidal performance and load effect is still lacking.In order to solve this problem,Ti O₂ and BiVO₄ were used as the research objects in this paper.The two materials were modified by silver to expand the corresponding range of visible light of the two materials and improve the carrier transfer level.Ag/BiVO₄ and Ag/Ti O₂ photocatalytic materials with high sterilization effect under visible light were prepared.On this basis,the main influencing factors of photocatalytic materials loaded on glazed tiles in toilets by spraying method were studied.Ag/BiVO₄ photocatalytic ceramic tiles and Ag/Ti O₂photocatalytic ceramic tiles were prepared at different temperatures.The effects of heat treatment parameters on the basic properties and sterilization properties of photocatalytic tiles were systematically discussed.The main research results of this paper are as follows:（1）Flower-like BiVO₄ and Ag/BiVO₄ with the size of 2-3μm and irregularly blocky Ti O₂ and Ag/Ti O₂ with the size of 12-20μm were synthesized by sol-gel method.The results of XRD and SEM showed that the prepared BiVO₄ and Ag/BiVO₄were monoclinic,and the crystal forms of Ti O₂ and Ag/Ti O₂ were rutile.The addition of Ag did not change the shape and crystal form of BiVO₄ and Ti O₂.SEM-EDS and XPS showed that Ag existed in BiVO₄ and Ti O₂ at+1 and 0,respectively.（2）The optical properties of Ag/BiVO₄ and Ag/Ti O₂ were analyzed by UV-Vis DRS.The results showed that the absorption edge and absorption intensity of Ag/BiVO₄and Ag/Ti O₂ were significantly stronger than those of BiVO₄ and Ti O₂,the band gap of the modified photocatalyst were narrower,and the band gap of Ag/BiVO₄ was the narrowest,indicating that Ag was conducive to expanding the visible light absorption range of BiVO₄ and Ti O₂,and the absorption performance of Ag/BiVO₄ was the best.（3）The results of XRD,tape test,scratch test and sterilization experiment showed that the crystal forms of BiVO₄,Ag/BiVO₄,Ti O₂ and Ag/Ti O₂ were not changed by temperature.With the increase of temperature,the adhesion of the photocatalytic coating on the surface of the photocatalytic ceramic tiles increased,but the sterilization effect decreased.The coating of Ag/BiVO₄ photocatalytic ceramic tile prepared at 650℃and Ag/Ti O₂ photocatalytic ceramic tiles prepared at 1000°C had best adhesion,and the sterilization rate reaches 100%and 99.719%under visible light for 2 h,respectively.These two photocatalytic ceramic tiles have good promotion prospects.（4）The results of SEM and AFM showed that high temperature causes agglomeration among photocatalyst particles and even mutual melting into denser structures,thus forming a more compact photocatalytic coating on the surface of ceramic tiles,which improved the adhesion of Ag/BiVO₄ and Ag/Ti O₂ on the surface of ceramic tiles.With the increase of temperature,the photocatalytic particles on the surface agglomerate and the particle size of the material increased,which lead to the roughness of the coating surface increased,but the high temperature made the materials melted,resulting in the decrease of the roughness of the coating surface.（5）The results of single-factor sterilization experiments of Ag/BiVO₄photocatalytic ceramic tiles prepared at 650℃and Ag/Ti O₂ photocatalytic ceramic tiles prepared at 1000℃showed that Ag/BiVO₄ photocatalytic ceramic tiles had the highest sterilization efficiency.Under the optimal sterilization conditions,the two kinds of photocatalytic ceramic tiles had excellent bactericidal effect on Escherichia coli,Staphylococcus aureus and other pathogenic bacteria.The coexisting-ions such as sulfate and nitrate,and the concentration of bacterial suspension had little effect on the bactericidal activity.The sterilization rate of Ag/BiVO₄ photocatalytic ceramic tiles reached 99.9991%after five cycles of sterilization,indicating that the prepared photocatalytic ceramic tiles had wide applicability and good stability.